WSN InstaChat is an experimental new kind of chat where you can watch others typing rich text in real time. Use rich text formatting, images, spell check, tables, bullet points, lists, Flash objects, smilies, and more in your chat. Collaborate with other people, either one on one or with a large group. Installation is as easy as copying the files to your Web server.

Kawaii Emoji Messenger is a multiplatform Facebook client based on the idea of bringing emoji to the desktop. It lets you use a full set of emoji in your Facebook conversations, statuses, and comments in the easiest way.

Liliko Chat is a fast and customizable Web chat system. It provides modern features such as desktop notifications, a responsive design, multiple languages and themes, and many more. Integration into existing community systems like phpBB 3 or MyBB is as simple as editing a config file.

WSChat is a simple Web chat system that uses PHP Websockets server code and a Javascript client HTML5 API to create a system similar to IRC for live interactive Internet text messaging between users via Web interface. It supports system domains, channels (with various modes), private messaging, and many other features. System data is stored in an SQLite database. It can easily be improved to make a powerful chat system.

Quak is a simple Jabber component (framework).
It connects to a Jabber server as a component and acts like a normal bot.
You can add plugins to make the bot react to several events (some simple
plugins are included).

NetIRC2 is an easy-to-use .NET IRC client library. It supports all major features relevant to making a chat client or bot. It has full support for synchronization contexts. You can use it from a Windows Forms or WPF GUI thread and chat events will be automatically dispatched, allowing you to completely ignore multithreading. It uses byte arrays internally, so mixed encodings can be handled. The IrcClient class can even be used as a component in the Forms Designer. Because it speeds up connect times with some IRC servers, an Ident server is included as well.

HexChat is an easy-to-use graphical IRC chat client for Windows and Unix based on XChat. It allows you to join multiple IRC channels (chat rooms) at the same time, talk publicly, have private one-on-one conversations, transfer files, etc.

Ybot is erlang bot software inspired by Github hubot. It supports IRC and XMPP transports and is extensible with plugins. Plugins can be written with Python, Ruby, or shell. It supports IRC chat, XMPP multi user chat, and 37 signals Campfire chat. It can simultaneously run any number of bots on different transports.